Kim K's Rear Sticks Out in Traffic -- Gets Bumped

The Tush was driving on the 101 freeway in L.A. last week, stuck in bumper to bumper traffic -- when she was hit by a motorcycle trying to weave in between cars. Sources tell TMZ the rider side-swiped the sick ride, popping the tire and scraping the rear end. The collision caused the rider to fall off his bike -- but he quickly got back on and took off! We're told Kim filed a report with the CHP.